Engine starter gearing



April l959 c. A. MENDENHALL 2 ,882,421

ENGINE STARTER GEARING 2 SheetsSheet 1 Filed Feb. 12, 1957 \o dnh lllll l l bk INVENTOR. he/lead.

A TonNEY April 14, 1959' c. A: MENDENHALL 2,882,421

ENGINE STARTER GEARING Filed Feb. 12, 1957 2 sheets-sheet 2 INVENTOR.

TTORNEY ENGINE STARTER GEARING Charles A. Mendenhall, Horseheads, N.Y., assignor to Bendix Aviation Corporation, Elmira Heights, N.Y.,

a corporation of Delaware Application February 12, 1957, Serial No. 639,801

1 Claim. (Cl. 290-38) The present invention relates to a heavy-duty starting system for internal combustion engines and more particularly to a two-stage starter control system.

In electrical starting systems of the automatically engaging type for heavy-duty installations using power sources of 24 volts or more, it is desirable to reduce the motor 3 which is grounded at 15 to complete the circuit through the battery 1. The motor 3 is thereby energized at a reduced voltage due to the voltage drop across the resistor 13, causing the motor to rotate with moderate acceleration. I 1

Closure of the switch 8 also sets in vibration a pendulous time delay device 16 which controls a pair of coninitial shock of engagement by energizing the starting motor in two stages. When this is done, it is customary to use some form of detent or latch member to momentarily prevent rotation of the drive pinion to thereby insure its traversal into mesh with the gear of the engine to be started.

A control system of this type is disclosed in the patent to Elkin 2,233,595 issued March 4, 1941 in which the pinion detent 58 is actuated by a solenoid which is energized by the voltage drop across the resistor 46 during the initial stage of operation.

It has been found in the commerical development and use of such systemsas heretofore constructed, that in cold weather starting it may require a very substantialbraking force applied to the pinion to prevent the pinion from initially rotating with the screw shaft which actuates it, and thus to insure traversal of the pinion into mesh with the engine gear. This entails the use of a powerful electromagnet to operate the pinion detent, which is expensive to provide and occupies valuable space.

It is an object of the present invention to provide a novel two-stage starter system embodying a latch means for positively preventing rotation of the pinion on initial energization of the starting motor, to thereby insure traversal of the pinion into mesh with the engine gear.

It is another object to provide such a device which requires only a comparatively small and inexpensive solenoid for operating the pinion latch.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a semi-diagrammatic representation of a starting system constituting a preferred embodiment of the invention, the starter gearing and latch mechanism therefor being shown in side elevation, partly broken away and in section;

Fig. 2 is a sectional view of the starter gearing taken substantially on the line 2--2 of Fig. 1; and

Fig. 3 is an illustration of the starter gearing similar to Fig. 1 showing the parts in cranking position.

In Fig. 1 of the drawing there is shown a starting system comprising a battery 1, an automatic switching device indicated generally by numeral 2, a motor 3, and starter gearing indicated by numeral 4 actuated by said motor to rotate a gear 5 of the engine to be started.

The battery 1 has one terminal grounded at 6, and is connected by a lead 7 to an electro-magnetic switch 8 in the circuit controller 2, which switch is arranged to be closed by a solenoid 9 upon closure of a manual switch 11. Closure of the switch 8 completes a circuit through a lead 12, a resistor 13, and a lead 14 to the tacts 17, 18. When the time delay 16 comes to rest with contacts 17, 18 in engagement, a circuit is completed from the lead 12 through a second solenoid 19 to the ground at 21, thereby causing closure of a switch 22 which bridges the resistor 13 bymeans of the lead 23. When this happens, the starting motor 3 is energized by the full battery voltage.

The starting motor 3 is provided with an extended armature shaft 24 on which a driving clutch member 25 is splined as indicated at 26. Clutch member 25 is provided with teeth 27 adapted to engage cooperating teeth 28 of a screw shaft 29 which is slidably journaled on the armature shaft 24, and held in engagement with the clutch member 25 by a spring member 31.

A pinion member 32 is slidably journalled on a re-' ducedextension 33 of the armature shaft for movement into and out of mesh with the engine gear 5. Means for actuating the pinion is provided comprising a control nut 34 threaded on the screw shaft 29 andrigidly connected to the pinion 32 by a barrel member 35. Longitudinal travel of the control nut and pinion in the meshing direction is limited by a stop nut 36 fixed on the armature shaft, and the backward movement of the clutch member 25 caused by the screw-jack action of the control nut and screw shaft is cushioned by a block 37 of elastically deformable material confined on the armature shaft by a sleeve 38 and thrust washer 39.

In order to prevent rotation of the pinion and barrel member during the initial rotation of the screw shaft 29, a plurality of radial projections 41 are provided on the control nut 34, and a latch member 42 is mounted in the housing 40 of the starting motor for radial movement into and out of the path of rotation of the projections 41 when the pinion and barrel member are in idle position.

The latch member 42 is normally maintained in retracted position as shown in Fig. l by means of a spring 43. In order to move it into operative position, the latch member 42 is beveled at its outer end as indicated at 44, and a plunger 45 having a rounded or tapered end is slidably mounted in the motor housing for movement substantially normal to the latch member 42 to engage and wedge the latch member into operative position as shown in Fig. 3.

Plunger 45 is normally maintained in retracted position by a spring 46 and is arranged to be actuated by a solenoid 47 the terminals of which are connected by the leads 48, 49 to the ends of the resistor 13. Solenoid 47 is thus energized by the voltage drop across said resistor during the initial stage of operation of the starting motor.

The wedging end of the plunger 45 is supported and guided by a plate member 51 which is retained by suitable means such as a lock ring 52 in the chamber 53 formed in the motor housing to receive the latch member 42.

In operation, starting with the parts as shown in Fig. 1, closure of the manual switch 11 completes the circuit through the solenoid 9 thus causing closure of the switch 8. Closure of switch 8 completes the circuit from the battery 1 through resistor 13 to the motor 3, thus causing the armature shaft 24 to start rotating. At the same time the solenoid 47 is energized by the voltage drop across the resistor 13, causing the plunger 45 to wedge the latch member 42 into operative position, whereby rotation of the pinion 32 and barrel member 35 is positively prevented by engagement with one of the abutments 41. The pinion and-barrel member assembly is thus traversed by the screw-jack action of the screw shaft 2 9 and control nut 34 until the pinion 32 is meshed with the engine gear 5, at which time the projections 41 have moved axially out of engagement with the latch member 42 as shown in Fig. 3.

When the switch 8 closed, it flicked and released the time delay device 16, sothat after a predetermined time delay, contacts 17, 18 come into operative engagement thus energizing the solenoid 19 to' cause closure of switch 22 which short circuits the resistor 13 and the solenoid 47. The starting motor is thus energized at the full battery voltage, I and the solenoid 47 is deenergized whereby the spring 46 withdraws the plunger 45 and permits the spring 43 to withdraw the latch 42.

Cranking then proceeds in the usual manner, and when the engine'start's the starting motor is deenergized by opening the manual switch 11 after which the starter gearing is returned toits normal position by the overrunning' action of the pinionand barrel member as driven by the engine gear. I

Although but one form of the invention has been shown and described in detail it will be understood that changes may be made inthe precise form and arrangement of the parts without departing from the spirit of the invention.

I claim: 7

A two-stage starting system for internal combustion engines comprising a ower shaft, a pinion movable thereon into and out of mesh with a gear of an engine to be started, means for actuating the pinion from the power shaft including a screw shaft, means connecting the screw shaft to rotate with the power shaft, a control nut threaded on the screw shaft, and a barrel member connecting the control nut to the pinion having a projection extending radially outside the barrel; and means for momentarily preventing rotation of the pinion, barrel and control nut assembly to ensure the travel of the pinion into mesh with the engine gear on rotation of the power shaft, including a latch member movable radially into and out of the path of movement of said projection While the parts are in idle position, a plunger movable substantially normally to the path of movement of the latch member and having wedging engagement therewith, means including a solenoid for actuating the plunger to move the latch into operative position and block it from releasing movement, and means for energizing the solenoid for a predetermined time after initial energization of the starting system; said projection being located out of operative relation to the latch when the pinion and barrel assembly are in meshing position.

References Cited in the file of this patent UNITED STATES PATENTS 2,233,595 Elkin Mar. 4, 1941 2,327,960 Christian Aug. 24, 1943 2,511,814 Miller June 13, 1950 2,704,458 Spencer Mar. 22, 1955 

